package Solution101_200.problem110.BalancedBinaryTree;

import common.TreeNode;

/**
 * @program Leetcode
 * @description:
 * @author: lishangsheng
 * @create: 2019/07/12 10:02
 */
public class BetterSolution {
    public boolean isBalanced(TreeNode root) {
        if (root == null) {
            return true;
        }

        return getHeight(root) != -1;
    }
    private int getHeight(TreeNode root) {
        if (root == null) {
            return 0;
        }
        int leftHeight = getHeight(root.left);
        if (leftHeight == -1) {
            return -1;
        }
        int rightHeight = getHeight(root.right);
        if (rightHeight == -1) {
            return -1;
        }
        if (Math.abs(leftHeight - rightHeight) > 1) {
            return -1;
        }
        return Math.max(leftHeight, rightHeight) + 1;
    }
}
